impotence vs weakness

impotence

noun
  • Powerlessness; incapacity. 

  • Inability to copulate or beget children; sterility, erectile dysfunction, etc. 

weakness

noun
  • The condition of being weak. 

  • An inadequate quality; fault 

  • A special fondness or desire. 

How often have the words impotence and weakness occurred in a corpus of books? (source: Google Ngram Viewer )